A kind of radio frequency matching network and the plasma processing chambers applied thereofTechnical field
The present invention relates to the radio frequency power source (RFpowersuppliers) and matching network (matchingnetworks) that are applied to plasma processing chambers, particularly relate to the radio frequency power source and matching network that can realize multiple frequency radio-frequency power (multiple-frequencyRFpower).
Background technology
In the art, plasma processing chambers that is dual or multi-radio frequency is utilized to be known.Usually, the RF bias power (RFbiaspower) of the plasma processing chambers reception of double frequency has the frequency lower than about 15MHz, its radio frequency source power (RFsourcepower) received has higher frequency, is generally 27 ~ 200MHZ.In this article, RF bias power (RFbiaspower) refers to the radio-frequency power for controlling ion energy and Energy distribution thereof.On the other hand, radio frequency source power (RFsourcepower) refers to the radio-frequency power for controlling plasma ions and dissociate (iondissociation) or plasma density.In certain embodiments, the offset frequency usually running etch plasma process chamber is that such as 100KHz, 2MHz, 2.2MHz, 13.56MHz, source frequency is such as 13.56MHz, 27MHz, 60MHz, 100MHz or higher.
In plasma reaction chamber practical work process, need the rf bias power supply providing frequency different, such as, under sometimes needing reaction chamber to be operated in the source frequency of 2MHz offset frequency and 60MHz simultaneously; And under sometimes needing reaction chamber to be operated in the source frequency of 13MHz offset frequency and 60MHz simultaneously, for the ease of selecting the RF bias power of different frequency, the output being typically employed in two RF bias power in prior art connects a relay, is disconnected and the RF bias power needed for closed selection by relay.But relay when rf bias power supply disconnects, just can carry out switching and select, and the disconnection of rf bias power supply can only will affect energy of plasma and distribution thereof.Therefore need in practical application to provide a kind of matching network that can realize instant switching rf bias power supply.
Summary of the invention
Summary of the invention part only provides the basic comprehension introduction to aspects more of the present invention and feature, but not entirety of the present invention is summarized, it is not especially for determining the present invention's key or main principle or limiting scope of the present invention, its object only for presenting concepts more of the present invention in simplified form, using the preorder described as hereafter more details.
In order to solve the problem, the invention provides a kind of switchable radio frequency matching network, for by two RF bias power when the bigoted power source of radio frequency without the need to disconnect, switchably put on the electrode of a plasma processing chambers, described radio frequency matching network comprises a resonant circuit, and described resonant circuit comprises an electric capacity, an inductance and a variable capacitance, regulates variable capacitance size, described resonant circuit can switch between the first impedance state and the second impedance state
At the first impedance state, described resonant circuit is in high impedance status to the second RF bias power, is in low impedance state to the first RF bias power;
At the second impedance state, described resonant circuit is in high impedance status to the first RF bias power, is in low impedance state to the second RF bias power.
Described resonant circuit comprises the parallel circuits of a capacitor and an inductor parallel join, described parallel circuits two ends connect a capacitor and an inductor respectively, described variable capacitance is coupled to ground between described RF bias power, comprises a coupling and the fixed capacity between ground and described RF bias power further.
Two described RF bias power can be provided by an independent radio-frequency power generator, also can be provided respectively by two radio-frequency power generators.
The present invention also provides a kind of plasma processing chambers run under two switchable RF bias power sources, comprising:
A reaction chamber, for be pumped into vacuum at it inside among produce plasma;
A bottom electrode, for coupling radio frequency energy in described plasma;
First radio-frequency power generator, it produces first offset frequency lower than 10MHz or one alternatively higher than described first offset frequency but lower than second offset frequency of 15MHz;
First matching network, it is for switchably putting on the electrode of a plasma processing chambers by two RF bias power;
Second radio-frequency power generator, it produces the radio frequency source power higher than 15MHz; And,
Second matching network, it comprises the input being coupled in described second radio-frequency power generator and the output being coupled in described bottom electrode.
The first described radio frequency matching network comprises a resonant circuit, described resonant circuit comprises an electric capacity, an inductance and a variable capacitance, regulate variable capacitance size, described resonant circuit can switch between the first impedance state and the second impedance state, at the first impedance state, described resonant circuit is in high impedance status to the second RF bias power, is in low impedance state to the first RF bias power; At the second impedance state, described resonant circuit is in high impedance status to the first RF bias power, is in low impedance state to the second RF bias power.
Described a kind of plasma processing chambers run under two switchable RF bias power sources, it comprises a second variable parallel capacitor be coupled to ground between described second radio-frequency power generator further.
Described first offset frequency is about 2MHZ, and described second offset frequency is about 13MHz, and the frequency of described radio frequency source power is any one in 27MHz, 60MHz and 100MHz.
Described plasma processing chambers, it comprises an antiresonant circuit further, between its described output being coupled in described second matching network and described bottom electrode, described antiresonant circuit is by tuning to make its centre frequency at about 13MHz, and its frequency bandwidth is 2MHz.
The invention has the advantages that: by adopting radio frequency matching network of the present invention, only regulate the size of wherein variable capacitance can realize the instant switching of radio frequency matching network at two kinds of impedance states, thus also can realize instant switching under ensureing the prerequisite that two RF bias power do not disconnect in RF bias power source, meet the needs of plasma processing chambers.
Accompanying drawing explanation
The accompanying drawing comprised in this specification, as the part of this specification, schematically illustrates embodiments of the present invention, and is used from specification one and explains and illustrate principle of the present invention.Accompanying drawing is intended to the principal character that described embodiment is diagrammatically described.The object of accompanying drawing does not also lie in the relative size of each characteristic sum institute elements depicted describing actual execution mode, and described element is not drawn in proportion.
Fig. 1 is the structural representation possessing hot-swap bias power frequency plasma process chamber according to an embodiment of the invention.
Fig. 2 schematically illustrates a radio frequency power matching network.
Embodiment
Fig. 1 shows the structural representation possessing the plasma processing chambers of hot-swap bias power according to a specific embodiment of the present invention, and described plasma processing chambers comprises the switchable radio frequency bias power source that two are coupled in a matching network.In FIG, two RF bias power sources 125 and 155 provide switchable rf bias frequency f 1 and f2 to reaction chamber 100 by matching network 140.Described rf bias frequency f 1 is generally 2MHz or 2.2MHz, and rf bias frequency f 2 is generally 13MHz (being 13.56MHz more accurately).Two rf bias put on bottom electrode 110 usually.In this way, the ion energy that present invention achieves a kind of improvement controls.Such as, for needing higher bombarding energy application scenario, the such as application of front end etching (front-endetch), the source of 2MHz can be utilized, and for needing the application scenario of softer bombardment, the such as application of rear end etching (back-endetch), can utilize being biased of 13MHz.Fig. 1 also shows a radio frequency source power source 135, and it runs for 3 times in frequency f, such as, and 27MHz, 60MHz, 100MHz etc.Described radio frequency source power source 135 is sent to reaction chamber 100 by matching network 150, and puts on bottom electrode 110.Described source power is for controlling plasma density, and namely plasma ion dissociates.
Structure shown in Fig. 1 achieves the application of reaction chamber double frequency (or f1/f3 or f2/f3).Such as, f1 can be 400KHz to 5MHz; F2 can be 10MHz to 20MHz, but is usually less than 15MHz; F3 can be 27MHz to 100MHz or higher.In the present embodiment, f1 is 2MHz, f2 be 13.56MHz, f3 is 60MHz.Structure described in the present embodiment makes to operate in technical process to be needed to switch between low frequency bias power and high frequency bias power to become very easy.
Fig. 2 schematically illustrates a radio frequency matching network, wherein three usable frequencies wherein two be switchably applied on the bottom electrode 110 of a plasma processing chambers.A high frequency f3 is coupled in described bottom electrode 110 by a match circuit 250 and an antiresonant circuit 230, and two lower frequency f1 and f2 and matching network 240 are coupled, described radio frequency matching network 240 comprises a resonant circuit 220, described resonant circuit 220 comprises the antiresonant circuit of a capacitor and an inductor parallel join, antiresonant circuit 220 two ends connect a capacitor 202 and an inductor 201 respectively, be coupled between capacitor 202 and rf frequency f1 and f2 a variable capacitance 205, regulate variable capacitance 205, described resonant circuit can switch between the first impedance state and the second impedance state, at the first impedance state, described resonant circuit radio frequency frequency f 2 is in high impedance status, radio frequency frequency f 1 is in low impedance state, by f1 and f3 coupling and bottom electrode 110, at the second impedance state, described resonant circuit radio frequency frequency f 1 is in high impedance status, and radio frequency frequency f 2 is in low impedance state, by f2 and f3 coupling and bottom electrode 110.By regulating variable capacitance 205, make rf frequency f1 and f2 also can realize instant switching when the bigoted power source of radio frequency does not disconnect.In the present embodiment, described rf frequency f1/f2 is provided, under realizing can running on frequency f 1 or f2 with immediately switching by an independent radio-frequency power generator.
Resonant circuit 220 comprises the capacitor of a scope between 100pF-200pF and the parallel circuits of the inductor parallel join of a scope between 10uH-20uH, parallel circuits 220 two ends connect the capacitor of a scope between 100pF-300pF and scope inductor at 1uH-3uH respectively, and described variable capacitance is coupled to ground between described RF bias power.
Described antiresonant circuit 230 enters 60MHz source for preventing energy from 13.56MHz power source.That is, when match circuit 240 is coupled in 2MHz bias source, offset frequency thirtyfold lower than the plasma source frequency of 60MHz, therefore it can not skip match circuit 234.But when matching network 240 is coupled in 13.56MHz bias power, offset frequency, closer to plasma source frequency f 3, may skip described match circuit 234.Therefore, the invention provides a kind of antiresonant circuit 230, it is formed by connecting by a capacitor and an inductance in parallel.In the present embodiment, work as f1=2MHZ, f2=13.56MHz, f3=60MHZ, the centre frequency of described antiresonant circuit 230 is 13MHz, and its variable or frequency bandwidth are Δ f=2MHZ.This prevent offset frequency 13.56 to leak (leakinto) and enter source power source f3.Described resonant circuit is a short circuit (shortcircuit) as 60MHz.
In fig. 2, variable parallel capacitor 215 is frequency f 3 and match circuit 234 cooperating.In the present embodiment, variable capacitor 205 and 215 utilizes variable vacuum capacitor (VARIABLEVACUUMCAPACITORS) to implement.Further, in the present embodiment, specific protected mode can be adopted to protect above-mentioned variable parallel capacitor.Fixed capacitor 206 parallel coupling is in shunt capacitor 205.Fixed capacitor 206 protects shunt capacitor 205 not affect by firing frequency electric current when being set as low capacitance to make it.Meanwhile, fixed capacitor 210 parallel coupling is in variable parallel capacitor 215.Fixed capacitor 210 protects shunt capacitor 215 not affect by firing frequency electric current when being set as low capacitance to make it.In the present embodiment, variable parallel capacitor 205 can change between about 30PF to 1500PF, and fixed capacitor 206 is set to about 100PF.Similarly, in the present embodiment, variable parallel capacitor 215 can change between about 10PF to 150PF, and fixed capacitor 210 is set as about 120PF.
Finally, should be appreciated that the process that above describes and technology not relate to any specific device inherently, and any appropriately combined of multiple assembly should be applicable to.Further, various types of fexible unit all can be employed according to content teaching herein.It is also favourable that manufacture special purpose device realizes methods described herein step.The present invention describes with reference to specific embodiment, and its all aspect all should be exemplary and indefiniteness.It will be understood by those of skill in the art that the various combination of hardware, software and firmware is all applicable to enforcement the present invention.Such as, described software can perform with a variety of program or script, such as compilation, C/C++, PERL, SHELL, PHP, JAVA etc.
The present invention describes with reference to embodiment, and its all aspect all should be exemplary but not determinate.In addition, by the specific embodiment of the invention described herein and enforcement, other execution modes of the present invention should be apparent for those skilled in the art.The different aspect of described execution mode and/or element can in plasma processing chambers field separately or use with combination in any.Above-mentioned specific embodiment should be regarded as being only exemplary, and scope and spirit of the present invention are then defined by claims.